Yesterday's bicycle ride from Shoreline to Mill Creek
The problem (unfortunately a long-standing one) with the Shoreline to Everett Interurban Trail is the poor signage: since this trail frequently switches between being a dedicated-use bike path and being merely a bike lane on a street, it's very easy to get confused. For what it's worth, the only good rule of thumb is that once the trail parallels I-5 near Cedar Valley, if you get too far away from I-5 any further north then you've taken a wrong turn (which, obviously, is what I did around Mill Creek, and I never did manage to find the trail again...). Realistically, the only satisfying way to deal with this trail is to take a printed copy of the Snohomish County Bike Map with you.
My average speed was pretty poor, what with all the stopping due to being unsure whether I was actually on the trail :)